Write to file from ArrayList

Question

I'm trying to write an ArrayList to a file in java. This is what I do in main class:

To write Strings into the ArrayList I do:

list.add(String);

Then, to write it to the file:

readWrite.writing(list);

list is: List<String> list = new ArrayList<String>();

readWrite references to this class where I have defined the methods to read/write to a file:

 public void writing(ArrayList listToWrite) throws IOException {
    fileOutPutStream = new FileOutputStream (file);
    write = new ObjectOutputStream (fileOutPutStream);
    for (int i=0; i<=listToWrite.size(); i++){
        write.writeObject(listToWrite.get(i));
    }
    write.close();
}

When trying it on the console, I'm getting this exception:

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 1, Size: 1
    at java.util.ArrayList.rangeCheck(Unknown Source)
    at java.util.ArrayList.get(Unknown Source)
    at //*I GET REFERENCED TO THIS LINE IN THE CODE ABOVE:* **write.writeObject(listToWrite.get(i));**

Joni · Accepted Answer · 2013-12-04 15:04:34Z

3

Be careful with your limits: with <= you go one item past the end of the list.

for (int i=0; i<listToWrite.size(); i++){

Then again, note that ArrayList is itself serializable. You could just write it to the file without looping:

write = new ObjectOutputStream(fileOutPutStream);
write.writeObject(listToWrite);
write.close();

answered Dec 4, 2013 at 15:04

Joni

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1 Comment

masmic Over a year ago

Works perfect! I'll try the suggestion

clyde · Accepted Answer · 2013-12-04 15:06:58Z

2

Might be best to just go with:

for (String str : listToWrite){
    // DO WORK HERE
}

That way you don't have to worry about all of that messy indexing business.

answered Dec 4, 2013 at 15:06

clyde

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Comments

Ben · Accepted Answer · 2013-12-04 15:09:00Z

1

Another solution would also be:

BufferedWriter outputWriter = new BufferedWriter(new FileWriter(filename));
outputWriter.write(Arrays.toString(array));

answered Dec 4, 2013 at 15:09

Ben

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